why the red background on some emails?

Some emails show up with a red background with no reason why. Makes it hard to read.

Hi, could you tell me if you are receiving these emails from one or multiple users?

Jan

They seem to be coming from one person using ‘The Bat!’ as the mail client.
This probably has something to do with it:

SATURDAY MORNING MAIL - SATURDAY 25/1/2014

S=
ATURDAY MORNING MAIL - SATURDAY 25/1/2014
from source view…

could you send me that email exported to .eml to [email protected] ?

Jan